September 2010 Techline

Where To Write
Address all correspondence to: Techline Four Wheeler, 831 S. Douglas St., El Segundo, CA 90245. You can also reach us by e-mail at fourwheelereditor@sorc.com; be sure to type the words "Tech Line" in the subject line. All submissions become the property of Four Wheeler, and we reserve the right to edit them for length, accuracy, and clarity. The editorial department also can be reached through the Web site at www.fourwheeler.com. Due to the volume of mail, electronic and otherwise, we cannot respond to every reader, but we do read everything.

Mystery Smell From Flat-Towed XJQ I have a '92 Jeep Cherokee with a 5.5-inch lift running 32x11.50/15 tires. It has the 4.0L motor and automatic transmission. I flat-towed my Jeep to Moab for a Labor Day event. When we got to there, I started to unhook it from the motorhome. We got a very distinct smell of burning rubber from what seemed like the power steering pump. No funny noises or anything, just the smell. We made a quick check of all fluids and everything seemed okay. The next morning we took off to get fuel, drinks, and to begin our day on the trails. The burning rubber smell went away after our stop at the gas station. We ran two trails over the weekend and had zero problems.

The same smell returned when I got home and unhooked the Jeep again, only this time the steering wheel was off-center. Had the alignment checked and it was okay-just had to re-center the steering wheel. Everything has been fine since. I was thinking maybe I burned up the power-steering pump somehow, but like I said, the Jeep has been fine. I am planning some more trips with the Jeep, flat-towing behind the motor home, and I sure would like to know where that smell is coming from so I can fix it. Any ideas?Duane Gutierrez
Roy, UT

A I am not really sure, but I can make a pretty good guess. I don't think the problem is in the power steering pump. There are a couple of clues here. The first is the smell of burned rubber, and the second is the steering wheel now being off-center. Being flat-towed means that the Jeep is pretty darn close to the back of the motor home and you cannot see the front of the Jeep-in particular, the front tires. Several things could be happening. Are you leaving the steering wheel and the ignition key in the Lock position? If so, when you're making a turn in the motorhome, the front tires of the Jeep have to slide sideways to also make the turn. Or if you are leaving the key so that the wheels are unlocked, the tire starts to follow when you turn, but especially in a tight turn, they don't come back very quickly and again the tires slide sideways. This side movement scrubs off rubber.

Could it be that the rubber smell just accumulated under the hood? Did you by any chance put your hand on the tires to check a temperature difference between the front and the rear tires? The fronts will be warmer if the vehicle is sliding sideways. Did you notice any unusual wear pattern on the front tires that would indicate that they were scrubbing sideways? I think that pulling the front of the Jeep sideways is the problem on both the rubber smell, and that the side-loading slightly bent one of the steering components, causing the steering wheel to be off-center.

How to solve the problem? Make sure that the steering wheel is unlocked. A longer towbar, and mounting it lower on the Jeep (or raising the ball mount location on the motorhome) will provide more leverage. Putting a bit more caster into the front axle of the Jeep will also help somewhat, as caster is what keeps the wheels straight when moving forward. Avoid backing when hooked to the Jeep. The rearward direction will cause the opposite effect and has a tendency to cause the tires to go into full lock in one direction.

Fuel Injector CleaningQ I would like your opinion on fuel injector cleaning. I own a '03 Dodge Ram 2500 with the 5.7L V-8 and five-speed manual. The truck has 122,000 miles, and I keep up with the required maintenance as suggested by the owner's manual. I have heard varying opinions on the subject, ranging from (a) using quality gas will keep the injectors clean to (b) having them cleaned by a professional every 60,000 miles. Since I bought the truck new, my mpg has remained constant, it idles at approximately 500 rpm, and the engine runs smooth without a miss. The local Dodge dealer charges $99 to clean the system and he said it takes about 30 minutes. I always use a quality brand of gas with 89 octane as recommended by the owner's manual. Also, since new, I have used Mobil 1 fully synthetic oil and also use the Mobil 1 extended performance oil filter.Gary Hepner
Schuylkill Haven, PA

A Sounds to me like you're doing everything right to maintain your truck. One of the first signs of injector problems is a rough idle and a loss of fuel mileage, neither of which you are experiencing at this time.

Just to be on the safe side, because I often buy gas at remote stations that don't pump a lot of fuel, I dump a can of a name-brand fuel injection cleaner in the fuel tank of my Jeep about every six months and haven't had any fuel injection problems in about 130,000 miles. Who knows if I would have if I had not put in the cleaner. I don't think that you have anything to worry about, and if it was my truck, I would pass on the dealer services.

Gas Or Diesel Engine Swap: Which Way To Go?Q I have an '86 Dodge Ramcharger 4x4 with a 318ci V-8 and auto tranny, and have been debating on whether to put a 440ci V-8 or a 12-valve Cummins into her. I've heard that it should just bolt into the motor mounts, but I will need to lift it due to clearance issues and will need new axles. I want some advice on this conversion-and how much you think it would cost to do it. Eric Yoder
Park Hills, MO

A There are lots of things to consider when making a swap of this kind. Let's take a minute and look at both engines. The 12-valve Cummins weighs in at just about 1000 pounds, makes between 160 to 215 horsepower and 400 to 440 lb-ft of torque in stock form. Naturally, this can be boosted with aftermarket modifications. Your best bet would be to get an engine/trans/transfer-case combination, as it would make the installation so much easier. If you go with the later-model engine, you will have to deal with intercooler mounting and exhaust system issues. You would also have to address the weight issue as far as frame strength and suspension changes needed. Yes, new motor mounts will have to be fabricated. There will also have to be some changes to the fuel system. A larger radiator will be needed for sure.

Then there is the matter of noise. As you're aware, the 12-valve motor is pretty darn noisy, so you're going to have to spend a lot of money on some high-quality insulation material. Cost: very expensive! Price will depend on the year of engine, how many miles on it, and, well, just how much you really want to pay.

As to the 440, I went through this a long time ago with another reader but can't seem to find my notes on the subject. Here is what I can remember. First off, it's a much easier swap. The engine weighs in at around 670 pounds, and makes anywhere from 220 to 375 horsepower and around 360 lb-ft of torque, depending on what it originally came in. Do keep in mind that the Cummins engine makes its peak horsepower and torque at a much lower rpm. You will also need new motor mounts, but because Chrysler did use these engines in Ramchargers, they may be still available from a dealer that keeps old new stock parts; you can also try Schumacher Creative Services (www.engine-swaps.com).

While you could use the present radiator by swapping the water inlet to the opposite side, I suggest going to a larger one because you're adding another 100-plus cubic inches that need to be cooled. The fuel system can remain the same, though perhaps you could increase the size of the fuel line. You're going to also have to change transmissions, even if they are TorqueFlite 727s (yours may be a 904) because the big-block has a different bolt pattern than the small-block, along with a new matching torque converter. Again, it's just as easy to buy a motor with the proper transmission already bolted behind it. There may be some interference with the valve cover on the left side and the power brake booster. There were a couple different sizes used, as I remember, and you will need the smaller one for proper clearance.

My choice would be to go with the 440 due to cost and ease of installation. Fuel mileage for the 440 will suck (at about 10 to 12 mpg) while the Cummins will get in the 17- to 20mpg range. But when you consider the added cost of the Cummins swap and the noise factor, the 440 seems the way to go.

Propane vs. EFI: Which Is a Better Conversion?Q I have a 1984 Toyota XtraCab 4x4 manual with a 22R four-cylinder in it. I have 5.29:1 gears, a spool in the rear, ARB Air Locker in the front, 39.5-inch IROKs and chrome-moly Birfield eliminator in the front; it also has a flatbed and 14-inch-travel Bilstein shocks.

I want to ditch the carb and go propane or fuel injection. It is 99-percent off-road driven. Which would be better to do? I live in Montana and I've heard elevation can affect the propane. Is that true? If propane is the better choice, who makes a good conversion kit for it? Will it make enough power to wheel comfortably?Jeff M.
Via fourwheeler.com

A Elevation has the same effect on an engine being powered by either gasoline or propane. It's not so much the fuel, but the lack of oxygen. Compare hiking at sea level and at 6,000 feet. It's a lot more difficult due to the lack of oxygen.

Now, I know the next question is going to be about the cold.

Well, I also live in Montana, and most of the houses around me heat with propane. However, the lower the temperature, the less vapor pressure there is available to push the gas down the line. While I know little about propane as a motor fuel, I believe that the regulators used on a vehicle are designed to handle the proper amount of flow, no matter what the air temperature is.

There is a company called Got Propane in Tempe, Arizona, (www.gotpropane.com) that has propane kits designed for Toyotas like yours. They claim no loss of power.

Most likely the EFI conversion will make more horsepower, but will be a bit more troublesome to do. Guess the best bet would be to pull the entire system and wiring harness off of a later-model vehicle and hope you're good at wiring.